The present invention relates to a system and method for renovating pipes by removing accretions or build up in the pipes and then coating the pipes with a coating material.
All types of pipes, such as water pipes, gas pipes, sewer pipes, industrial fuel, chemical manufacturing plant pipes, and the like, are susceptible to build up of accretions or scale on the inner surface of the pipe. One of the reasons for this is corrosion or rust of the pipe surface. Another reason for scale build-up is the deposit of accretions from the material flowing through the pipe onto the pipe surface, such as lime or other deposits of solids from water in a water pipe. These accretions lead to a narrowing of the pipe diameter, reducing the throughput, and the formation of pits, ultimately jeopardizing the pipe integrity and leading to premature failure of the pipe system.
Renovating existing pipes will reduce the need for a complete or partial replacement of a piping system. This is of great advantage where pipes are installed below the ground, inside walls, or in shafts. The only thing that needs to be done is to dismount the instruments and devices at each end of the pipe and to mount them again after the pipe is cleaned and coated. Various pipe renovating systems and methods have been proposed in the past. In some cases, compressed air carrying particles of abrasive material is blown through the pipe. Such a method is described, for example, in U.S. Pat. No. 5,924,913 of Naf. The interior of the pipe is subsequently coated with an adhesive resin, such as an epoxy resin, which is also applied by use of compressed air to blow it through the pipe.
Processes using compressed air in this way can only be used on relatively small diameter pipes, and this cleaning technique can easily result in blocking of the pipe, or major leaks in the pipe when weakened after cleaning by constant high pressure. Pipes may not be adequately cleaned by such a method when major frictional resistance occurs in the pipe system.
U.S. Pat. No. 5,924,913 of Reimelt attempts to overcome these problems. In this method, cleaning abrasives are moved back and forth in the pipe by means of an alternating pressure drop. This may be done by alternately applying a vacuum to opposite ends of the pipe, or alternately supplying compressed air to opposite ends of the pipe. However, this technique can also result in blockages. When an abrasive agent is repeatedly moved back and forth, it will gradually become mixed with the accretions removed from the pipe surface, diluting or reducing the cleaning effect.